1. Field of the Invention
This invention relates to high protein, microbiologically stable, intermediate moisture food products in chunk form which are particularly useful as a pet or animal food.
2. Description of the Prior Art
Pet food products in general are divided into three general classes. They include the so-called dry pet food products, usually in meal or granular form which contain less than 15% moisture, most commonly about 10% moisture. The dry products are packaged and stored in bags and are resistant to spoilage if kept dry.
The high moisture products containing 65-75% moisture are generally sold as canned products and require retorting (cooking) in the canning operation to prevent spoilage.
The more recent intermediate moisture food products are those which contain between about 15 and 45% moisture. These products are in general stabilized by the use of soluble additives to produce a water activity (A.sub.w) sufficient to prevent bacteriological growth and consequent spoilage of the food products when packaged in moisture impermeable, flexible bags or wrappings. The bacterial growth and consequent product spoilage is precluded by additives such as sugar or low molecular weight polyhydroxy alcohols, including, for example, propylene glycol and glycerol. While the use of these soluble additives is effective to control conventional bacteriological growth, it is also necessary to control fungi, yeast and mold which can proliferate on systems which have been stabilized against bacteriological attack. The control of such molds, yeast and fungi is achieved by the addition of an antimycotic agent such as, for example, potassium sorbate, or the like.
Patents relating to the use of sugar stabilizers and antimycotic agents for intermediate moisture pet foods include Burgess et al., U.S. Pat. No. 3,202,541, No. 3,482,985, No. 3,615,652; Buck et al., U.S. Pat. No. 3,653,908, No. 3,489,574 and No. 3,516,838. Zukerman, U.S. Pat. No. 4,022,915, describes an intermediate moisture food product stabilized by the use of 5 to 15% polyhydroxy alcohol. The Zukerman method involves the hot processing and expansion of a mixture of cooked farinaceous and proteinaceous materials admixed with polyhydroxy alcohol and extruded under pressure to produce a low bulk density product which is formed into chunks, coated with fat and packaged.